Cars and rockets built before builds were recorded have no subkey and no
ugc_modular_build row, so the client has no blueprint id to ask for their
icon with. When a character loads, such an item (a ModularBuildComponent
createdLOT with assemblyPartLOTs but no subkey) gets what a new build
gets: a persistent id as its subkey and a ugc_modular_build row with its
modules and owner. The next save keeps the subkey; nothing is dropped.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>